Re: Dom0 starvs DomU

[tg%gmplib.org@localhost (Torbjörn Granlund)]

Greg Troxel <gdt%ir.bbn.com@localhost> writes:

  The other thing to do is run 'systat vmstat' which will show IOPS on
  each disk.
  
  I find it really funny that accesses to one disk would mess up
  another.   I wonder if there is some locking error in the code
  someplace.
  
I suspect that the problem is not with disk op starvation but that CPU
load in Dom0 hurts I/O in a DomU.  Playing with iostat suggests that.
Perhaps each I/O operation on behalf of Xen needs a full tick in this
situation...?

  Have you tried uses /dev/rwd1d instead of wd1d?  Maybe that's wrong, but
  I would expect the raw device.

I think you're right.  Fortunately, NetBSD is not fooled.  This is from
/var/log/xen/qemu-dm-shell.log:

Using file /dev/wd1d in read-write mode
/dev/wd1d is a block device, using /dev/rwd1d
...

-- 
Torbjörn
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